A computer failure in the nation's air-traffic control system caused severe flight delays along the East Coast Friday, the Federal Aviation Adminstration said.

A computer system in Atlanta that processes pilots' flights plans and sends them to air-traffic controllers failed late Thursday or early Friday, FAA spokeswoman Diane Spitaliere said. The agency rerouted the system's functions to another computer in Salt Lake City, which overloaded due to the increased volume of data, magnifying the problem.

The FAA could not immediately calculate the number of flight delays caused by the problem, which was made worse by bad weather, Spitaliere said.

Although the computer problem was fixed shortly before 11 a.m. Friday, its impact lingered on into the late afternoon, especially in New York, where computer systems took two extra hours to get back online, Spitaliere said. She said the flight delays in the rest of the country were not as severe.

Doug Church, a spokesman for the National Air Traffic Controllers Association, said the problem forced controllers to enter flight information manually, which he described as a time-consuming practice. "With some of these East Coast airports, nothing is getting in right now," Church said Friday afternoon.

AMR Corp.'s American Airlines spokesman Tim Wagner acknowledged the computer troubles and said the nation's largest carrier experienced about 50 cancellations on the East Coast, with LaGuardia departures being hit the hardest.

Betsy Talton, a spokeswoman for Delta Air Lines Inc., said the Atlanta-based airline was experiencing delays of roughly two hours Friday in the Northeast, but she attributed the backlog to thunderstorms.